When Italy declared war on 10 June 1940, the Tenth Army consisted of five divisions and the Fifth Army consisted of nine. After the Fall of France at the end of June, several divisions were transferred from the Fifth Army to strengthen the Tenth Army, which was increased to ten divisions.

In December 1940 during Operation Compass, the British counter-attacked in what initially was to be a five-day raid against the Italian camps in Egypt. The Italian camps were overrun and the rest of the Tenth Army was pushed further and further back into Italian Libya. Many Italian soldiers surrendered once the British troops encircled them in static fortified garrisons at places like Bardia and Tobruk.

O'Connor had this ad hoc force under the command of John Combe leave the coastal roads at Gazala and take a shortcut across the desert, to block the Italian army's retreat, while the Australian 6th Division continued the coastal pursuit. The force was delayed by the harsh terrain, so Combe Force, a lighter, faster element was detached to complete the interception, leaving the tracked vehicles to follow.

The first elements arrived at Msus late on the afternoon of 4 February and cleared the local garrison. During the following night and day the advance continued and the British artillery and infantry were in position across the coast road by 4 pm on 5 February. The head of the retreating Italian column arrived 30 minutes later.

The Italians were stunned to find the British force blocking them at Beda Fomm, whose strength they greatly overestimated. With the Australians in pursuit, a desperate battle ensued, in which newly arrived Fiat M13/40 medium tank battalions were thrown against the British positions, at great loss. In the afternoon of 6 February, the 7th Armoured Division tanks arrived and harassed the Italian eastern flank.

On the morning of 7 February, the Italians attempted a final, desperate attempt to break through. By this stage, the British units were almost out of food, petrol and ammunition. The British blocking line was almost breached and convinced of the overwhelming size and strength of the blocking force, the encircled Italian units surrendered. The Tenth Army was destroyed.[1]